1. Field of the Invention
The present invention relates to a mower. More particularly, the invention provides two sets of cutting blades, the first located at a higher level above the ground than the second. The first set of cutting blades is unencumbered by a skirt, thereby resisting clogging. The second blade leaves grass and brush at a final desired height above the ground.
2. Description of the Prior Art
Cutting of grass and brush for aesthetic or other purposes has long been the subject of many machines adapted for mowing. Commensurate with the area to be mowed, mechanized mowers have been provided with ever increasing sources of power and drive. Among the simplest of these machines is a manually propelled, powered mower having a singular blade directly driven by a motor shaft. The motor is typically a single cylinder internal combustion engine, or may be electric.
For mowing more extensive areas, self-propelled mowers have been provided. To further reduce the effort of the operator, riding mowers have been developed, and mowing units have been made attachable to tractors. To further increase the area which is cut in a single pass, plural rotary cutting blades have been ganged. This increases the span of the cutting blades, while minimizing the diameter of any one rotary blade. It also provides better conformity of cutting blades to uneven terrain.
A mower described in U.S. Pat. No. 3,601,958, issued to Earl O. Roof on Aug. 31, 1971, has three blades driven by V-belts, and enclosed within a hood formed by cooperating. The center blade, considered from the front view, is located forwardly of the right and left side blades. The purpose of this arrangement is to cause the respective swaths to overlap. There is no teaching that the various blades should cut to different heights, apart from accommodation of uneven terrain. By contrast, this teaching is central to the present invention. In the present invention, the first blades to encounter and cut grass and brush are not surrounded by a guard, hood, or skirt. By contrast, the blades of the Roof mower are so enclosed, except for a cuttings discharge chute.
Self-propelled, powered vehicles having attachable mowing units are also shown in U.S. Pat. Nos. 4,969,319, issued to Wayne R. Hutchison et al. on Nov. 13, 1960, U.S. Pat. No. 5,016,722, issued to Shigeru Morita et al. on May 21, 1991, and U.S. Pat. No. 5,042,236, issued to Gary R. Lamusga et al. on Aug. 26, 1991. Hutchison et al. provide a front or rear mounted mowing unit attached to a tractor unit by arms, and driven by a V-belt and pulley system. In an alternative embodiment, hydraulic power is employed to rotate the cutting blades. However, there is no teaching of sequentially disposed cutting blades, and therefore, of cutting grass first to one height, and subsequently to a lower height, as is practiced in the present invention. Also unlike the present invention, all blades are enclosed within a safety guard.
The mower of Morita et al. features triplex blades rotated by a V-belt system. The blades are arranged abreast of one another, all blades encountering and cutting grass simultaneously. The blades are covered by a hood, which is equivalent structurally to a typical safety guard, for the purpose of constraining cuttings to be collected in a grass catcher. There are no first and subsequent cutting blades, the first blade being unencumbered by a hood or guard, as occurs in the present invention.
The mower of Lamusga et al. also features plural blades disposed abreast, each enclosed in a guard. Lamusga et al. also lack first and subsequent cutting blades, the first blades being unencumbered by guards, as found in the present invention.
A mowing unit attachable to a fork lift or the like, and which has a singular blade, is described in U.S. Pat. No. 5,005,344, issued to Doc J. McCracken on Apr. 9, 1991. This blade is provided with outermost auxiliary blades intended to yield if a resisting object is encountered. The single blade must by definition cut at one elevation, unlike the first and subsequent blades of the present invention. Also unlike the present invention, this singular blade is partially enclosed in a housing or guard.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.